Revert "arm64: fpsimd: Enable FP(floating-point) settings for msm8996"

This reverts commit 2dae58c4af ("arm64: fpsimd: Enable
FP(floating-point) settings for msm8996").

Feature is not applicable to msmcobalt and only applicable
to MSM8996.

CRs-Fixed: 1054373
Change-Id: I8f21787f0a45dd9f7be8986b4f332f498add3203
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>

arch/arm64/Kconfig

@@ -513,16 +513,6 @@ config ARM64_64K_PAGES
 
 endchoice
 
-config ENABLE_FP_SIMD_SETTINGS
-	bool "Enable FP(Floating Point) Settings for Qualcomm MSM8996"
-	depends on ARCH_MSM8996
-	help
-	  Enable FP(Floating Point) and SIMD settings for the MSM8996 during
-	  the execution of the aarch32 processes and disable these settings
-	  when you switch to the aarch64 processes.
-
-	  If you are not sure what to do, select 'N' here.
-
 choice
 	prompt "Virtual address space size"
 	default ARM64_VA_BITS_39 if ARM64_4K_PAGES

arch/arm64/include/asm/elf.h

@@ -23,7 +23,6 @@
  */
 #include <asm/ptrace.h>
 #include <asm/user.h>
-#include <asm/fpsimd.h>
 
 typedef unsigned long elf_greg_t;
 
@@ -178,13 +177,7 @@ typedef compat_elf_greg_t		compat_elf_gregset_t[COMPAT_ELF_NGREG];
 					 ((x)->e_flags & EF_ARM_EABI_MASK))
 
 #define compat_start_thread		compat_start_thread
-#define COMPAT_SET_PERSONALITY(ex)					\
+#define COMPAT_SET_PERSONALITY(ex)	set_thread_flag(TIF_32BIT);
-do {									\
-	if (current->mm)						\
-		fpsimd_enable_trap();					\
-	set_thread_flag(TIF_32BIT);					\
-} while (0)
-
 #define COMPAT_ARCH_DLINFO
 extern int aarch32_setup_vectors_page(struct linux_binprm *bprm,
 				      int uses_interp);

arch/arm64/include/asm/fpsimd.h

@@ -81,18 +81,6 @@ extern void fpsimd_save_partial_state(struct fpsimd_partial_state *state,
 				      u32 num_regs);
 extern void fpsimd_load_partial_state(struct fpsimd_partial_state *state);
 
-#ifdef CONFIG_ENABLE_FP_SIMD_SETTINGS
-extern void fpsimd_disable_trap(void);
-extern void fpsimd_enable_trap(void);
-extern void fpsimd_settings_disable(void);
-extern void fpsimd_settings_enable(void);
-#else
-static inline void fpsimd_disable_trap(void) {}
-static inline void fpsimd_enable_trap(void) {}
-static inline void fpsimd_settings_disable(void) {}
-static inline void fpsimd_settings_enable(void) {}
-#endif
-
 #endif
 
 #endif

arch/arm64/kernel/entry-fpsimd.S

@@ -64,36 +64,4 @@ ENTRY(fpsimd_load_partial_state)
 	ret
 ENDPROC(fpsimd_load_partial_state)
 
-#ifdef CONFIG_ENABLE_FP_SIMD_SETTINGS
-ENTRY(fpsimd_enable_trap)
-	mrs x0, cpacr_el1
-	bic x0, x0, #(3 << 20)
-	orr x0, x0, #(1 << 20)
-	msr cpacr_el1, x0
-	ret
-ENDPROC(fpsimd_enable_trap)
-ENTRY(fpsimd_disable_trap)
-	mrs x0, cpacr_el1
-	orr x0, x0, #(3 << 20)
-	msr cpacr_el1, x0
-	ret
-ENDPROC(fpsimd_disable_trap)
-ENTRY(fpsimd_settings_enable)
-	mrs x0, s3_1_c15_c15_0
-	orr x0, x0, #(1 << 31)
-	isb
-	msr s3_1_c15_c15_0, x0
-	isb
-	ret
-ENDPROC(fpsimd_settings_enable)
-ENTRY(fpsimd_settings_disable)
-	mrs x0, s3_1_c15_c15_0
-	bic x0, x0, #(1 << 31)
-	isb
-	msr s3_1_c15_c15_0, x0
-	isb
-	ret
-ENDPROC(fpsimd_settings_disable)
-#endif
-
 #endif

arch/arm64/kernel/entry.S

@@ -427,7 +427,7 @@ el0_sync_compat:
 	cmp	x24, #ESR_ELx_EC_IABT_LOW	// instruction abort in EL0
 	b.eq	el0_ia
 	cmp	x24, #ESR_ELx_EC_FP_ASIMD	// FP/ASIMD access
-	b.eq	el0_fpsimd_acc_compat
+	b.eq	el0_fpsimd_acc
 	cmp	x24, #ESR_ELx_EC_FP_EXC32	// FP/ASIMD exception
 	b.eq	el0_fpsimd_exc
 	cmp	x24, #ESR_ELx_EC_PC_ALIGN	// pc alignment exception
@@ -498,17 +498,6 @@ el0_fpsimd_acc:
 	mov	x1, sp
 	bl	do_fpsimd_acc
 	b	ret_to_user
-el0_fpsimd_acc_compat:
-	/*
-	 * Floating Point or Advanced SIMD access
-	 */
-	enable_dbg
-	ct_user_exit
-	mov	x0, x25
-	mov	x1, sp
-	bl	do_fpsimd_acc_compat
-	b	ret_to_user
-
 el0_fpsimd_exc:
 	/*
 	 * Floating Point or Advanced SIMD exception

arch/arm64/kernel/fpsimd.c

@@ -88,23 +88,14 @@
  *   whatever is in the FPSIMD registers is not saved to memory, but discarded.
  */
 static DEFINE_PER_CPU(struct fpsimd_state *, fpsimd_last_state);
-static DEFINE_PER_CPU(int, fpsimd_stg_enable);
 
 /*
  * Trapped FP/ASIMD access.
  */
 void do_fpsimd_acc(unsigned int esr, struct pt_regs *regs)
 {
-	fpsimd_disable_trap();
+	/* TODO: implement lazy context saving/restoring */
-	fpsimd_settings_disable();
+	WARN_ON(1);
-	this_cpu_write(fpsimd_stg_enable, 0);
-}
-
-void do_fpsimd_acc_compat(unsigned int esr, struct pt_regs *regs)
-{
-	fpsimd_disable_trap();
-	fpsimd_settings_enable();
-	this_cpu_write(fpsimd_stg_enable, 1);
 }
 
 /*
@@ -144,11 +135,6 @@ void fpsimd_thread_switch(struct task_struct *next)
 	if (current->mm && !test_thread_flag(TIF_FOREIGN_FPSTATE))
 		fpsimd_save_state(&current->thread.fpsimd_state);
 
-	if (__this_cpu_read(fpsimd_stg_enable)) {
-		fpsimd_settings_disable();
-		this_cpu_write(fpsimd_stg_enable, 0);
-	}
-
 	if (next->mm) {
 		/*
 		 * If we are switching to a task whose most recent userland
@@ -166,11 +152,6 @@ void fpsimd_thread_switch(struct task_struct *next)
 		else
 			set_ti_thread_flag(task_thread_info(next),
 					   TIF_FOREIGN_FPSTATE);
-
-		if (test_ti_thread_flag(task_thread_info(next), TIF_32BIT))
-			fpsimd_enable_trap();
-		else
-			fpsimd_disable_trap();
 	}
 }